This invention relates to a fuel reforming system for a fuel cell and method of stopping the system.
JP-A-H5-275105 published by the Japanese Patent Office in 1993 discloses a technique wherein the fall in a fuel cell plant temperature is reduced and the startup time of the plant is shortened by recirculating high temperature gas at the outlet of a carbon monoxide removal device upstream of a reformer when the system stops.
However, if it is attempted to apply this prior art stopping method to a relatively lightweight universal fuel reforming system for a fuel cell such as that installed in an automobile, it is necessary to install a special pipe or flow rate change-over valve to recirculate gas from the carbon monoxide removal device upstream of the reformer and the construction of the reforming system becomes complex, which interferes with the compactness and low cost of the reforming system.
It is therefore an object of this invention to provide a fuel reforming system and method of stopping the system which permits the startup time of the reforming system to be shortened without making the system complex or too large.
In order to achieve above object, this invention provides a method of stopping a fuel reforming system with a reformer which generates hydrogen supplied to a fuel cell wherein fuel, water and air are supplied, and a partial oxidation reaction and steam reforming reaction are simultaneously performed, comprising stopping the supply of fuel and water to the reformer so as to raise the catalyst layer temperature of the reformer by performing a partial oxidation reaction with the remaining fuel and air in the reformer, and stopping the supply of air to the reformer after the catalyst layer temperature has risen.
According to an aspect of this invention, this invention provides a fuel reforming system, comprising a reformer which generates hydrogen supplied to a fuel cell wherein fuel, water and air are supplied, and a partial oxidation reaction and steam reforming reaction are simultaneously performed, a first supply mechanism which supplies fuel and water to the reformer, a second supply mechanism which supplies air to the reformer, and a controller which functions to perform a partial oxidation reaction with the remaining fuel and air in the reformer by stopping the supply of fuel and water to the reformer from the first supply mechanism when the system is stopped, and stop the supply of air to the reformer from the second supply mechanism after the catalyst layer temperature has risen.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.